In a mobile communication system, a call processing node performing call processing stops according to schedule for the purpose of maintenance or the like or suddenly stops due to, for example, occurrence of failure. In a call processing system for the mobile communication system, redundancy is required so that a communication call is not disconnected in any of such cases. Therefore, a call processing node (act) of an operation system and a call processing node (sby) of a standby system are provided to perform redundancy (multiplexing) of a device (for example, see Patent Literature 1).